Thermosensitive poly(N-isopropylacrylamide) (PNIPAm)-coated gold nanoparticles (AuNPs) were prepared by self-assembly of the azobenzene-terminated PNIPAm on the surface of the alpha-cyclodextrin (alpha-CD)-capped AuNPs via the host-guest molecular recognition between a-CD and azobenzene. Reversible attachment-detachment of azobenzene-terminated PNIPAm on the surface of alpha-CD-capped AuNPs was achieved when subjected to visible and UV light irradiation alternately, which endowed thermosensitive AuNPs with tunable smart properties.